Liquid crystal displays are, of course, known for numeric displays and alphanumeric displays. Multiplexing of such displays is also well-known as indicated by the article entitled--Multiplexing Liquid--Crystal Displays on pages 113-121 of Electronics Magazine (McGraw-Hill Publication) for May 25, 1978.
In that article, an approach to multiplexing a numeric character with its characteristic seven segment display is shown. It is also well-known that by applying the energizing voltage in pulses at a sufficiently high frequency to different segments, the pulsed segments appear to be continuously illuminated to the eye of a viewer. See U.S. Pat. Nos. 3,781,863 issued Dec. 25, 1973 to K. Fujita, and 3,945,001 issued Mar. 16, 1976 to G. Shimakawa.
Other two-plane displays using colloidal or fluid suspensions in place of the liquid crystal are also known as shown by U.S. Pat. Nos. 3,655,267 to Forlini as issued Apr. 11, 1972 and 3,708,219 to Forlini et al issued Jan. 2, 1973.